In computer science preemption means the ability to withdraw a resource from its owner before the owner gives it up voluntarily. Most often this resource is the processor and the owner a task or process but also complete devices can be a resource (cf. HAVi's preemption scheme).

The ability to preempt has important consequences for deadlock prevention and available process scheduling strategies. The later are therefore often divided into preemptive and non-preemptive ones. Round-Robin is a preemptive strategy and Shortest Job First is the optimal non-preemptive strategy with respect to responsiveness. The optimal preemptive strategy is left as an exercise for the reader.